Resistance box



NOV. S, 93@ E, EANQQLY LSZ RESISTANCE BOX Filed Feb. 152.7 1925 Patented Nov. 18, 1930 UNITED STATES ERICH BANDOLY, OF CHCAGO, ILLNOES, ASSIGNOR TO CENTRAL SCENTFG CGM- PANY, GF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS RESSTANCE BOX Application led February 8, 1926.

This invention relates to resistance boxes and has for its principal objects to simplify the process of manufacturing and reducing the cost of production; to improve the mounting of the lugs to which the coils are connected; to make the plug openings self-cleaning; and to cool the coils.

Further objects and advantages of the invention will become apparent as the disclosure proceeds and the description is read in connection with the accompanying drawings illustrating the preferred embodiment of the invention in which F ig. 1 is a plan view of a resistance box, and

Figs. 2 and 3 are sectional views taken on the lines 2 2 and 3 3 respectively, of 1.

ln this preferred form the enclosed casing, or box proper includes a top 10, sides 11, and ends 12 made in one piece of moldable insulating material. rlhe lower edges of the sides and ends are rabbeted, as indicated at 13, to receive a perforated bottom 14. Below the bottom and between the corners, the sides and ends are cut away, as indicated at 15, which has the effect or" forming feet 16 at the corners of the box and elevating the intermediate portions to facilitate the ingress of air through the perforations 17 in the bottom 111.

The spools 18 are provided with shanks 19 having a driving fit with lugs 2O and 21. rl"he wires forming the coils 22 are wound on the spools and have their ends connected to the stems 23 and 24 of the spools, as best illustrated in F ig. 2. The end spools at the right are electrically connected by a strap 25 inserted between the spools and the lugs 21. @ne end of each coil on the spools at the left is connected with a rod 2G mounted in a lug 27 and electrically connected by a strap 28 with a binding post 29.

rlhe sides of the lugs 20, 21 and 27 are provided with pockets 30 into which the melilable insulating material flows to interlock them with the top of the box and secure them firmly in place.

Adjacent faces of the lugs are provided with inclined and rounded recesses 31 which Serial No. 86,867.

to receive plugs 32 for conducting material by which the lugs may be electrically connected to shunt out the corresponding resistance coils.

ln making a resistance box in this preferred form7 the lugs 20, 21 and 2"? are made fast within the cavity of a die, a suitable quantity of moldable insulating material is inserted a second die cooperates with the first die to form the material, and heat is applied to cure it.

ln this way the lugs are securely mounted in the supporting structure with their adjacent surfaces in intimate contact without strain, and are firmly held in proper spaced relation.

rlhe fastening is sufficiently strong to prevent any movement of the lugs under the wedging action of the plugs, which often causes looseness when the lugs are secured to the supporting structure in the usual way. By making the upper surfaces of the lug flush with the upper surface of tne top, the entire face of the resistance box may be quickly and cheaply finished as a unit in one and the same finishing operation, which effects a considerable saving in the cost of manufacture.

The plug openings extend entirely through the top of the box and thus irevent dust, or other foreign matter, from accummulating therein and interfering with the proper seating of the plugs. rlhey also permit air currents to pass up through the box along the coils that are in service and outA through the corresponding plug openings, keeping the coils cool and increasing the accuracy of readings made with the instrument.

rIhe coils that are not in service may also be subjected to cooling drafts by providing passages 33 at each side of the plug openings formed by the rounded vrecesses 31. rlhese passages may be formed in the molding opera-tion, suitable means being provided to prevent the moldable material from flowing between the ends of the lugs 20, 21 and 27. This also has the advantage of protecting the reamer, or other tools, used in finishing the plug openings, from being chilled by the moldable material.

The moldable insulating material may vary with personal taste, but the composition of a phenolic condensation with a filler now upon the market lends itself most readily to manufacture according to this invention.

Some of the advantages of the invention may be had without making the sides and ends integral with the top or without extending the plugs through the top, and various other changes will readily suggest themselves to those skilled in the art. Therefore, while I have used specific description and illustrations to disclose the invention, l do not wish anything herein to be construed as limiting the protection secured by the patent other than is required by the prior art. Y

l claim as my inventio-n i. A ventilated resistance box having top, side, and end walls molded as an integral structure with an elongated slot in the top of the box and a series of oval lugs having recesses in the side thereof, said lugs being of conducting material disposed within the slot and having the walls of the slot molded in interlocking engagement therewith, said interlocking engagement forming means independent of frictional resistance for resisting the relative movement of said lugs and top in every direction, said'lugs being disposed in spaced relation and defining openings therebetween for receiving tapering plugs of conducting materiah 2. A ventilated resistance box having top, side7 and end walls molded as an integral structure, the top having an elongated slot molded therein, and a series of conductor lugs imbedded in the slot portion of the top during the molding thereof and interlocled withthe walls of the'slot, the lugs being spaced to define upright plug receiving openings, and the walls of the slotbeing recessed between adjacent lugs laterally of said openings and in communication therewith to provide upright Ventilating passages.

3. Aventilated resistance box having top, side, and end walls molded as an integral structure,the top of the box having an elongated slot molded therein, a separate perforate Ventilating bottom supported above the lower Vedges of the side and end walls, the space below said bottom being in communication with the atmosphere, and a plurality of lugs of conducting material disposed in the slot and imbedded in the walls thereof and disposed in spaced'relation to receive conductor plugs, the walls of the slot being recessed vertically entirely through said top between the lugsto provide upright ventilating passages laterally of the spaces for receiving said plugs and' in communication therewith.

4. A resistanceboir having a top of molded material Vprovided with an elongated slot weies therethrough having a plurality of enlargements forming shoulders therein, lugs Vof conducting material in said enlargements engaging said shoulders for preventing movement of said lugs longitudinally of said slot in either direction, the walls of said slot being molded in interlocking-engagement with said lugs for preventing movement thereof transversely of the plane of said top, the adjacent portions of said. lugs being recessed to form. openings for receiving plugs therein.

5. A resistance box having a top of molded material provided with an elongated slot extending therethrough, a plurality of lugs of conducting material molded in said` slot and having their upper ends flush-with the upper surface of said top, each of said lugs being recessed at opposite portions tl'iereof, the adjacent recesses of each pair of lugs forming a socket for receiving a plug of conducting material, said slots being provided with lateral extensions fo `ming shoulders for preventingmovement of said lugs longitudinally of said slots and the walls of said slots being molded in interlocking engagement withv said lugs for. preventing movement thereof transversely ofthe plane of said top.

In testimony whereof I affix' my signature.

ERICH BANDOLY. 

